Gaseous electric discharge device



July 20, 193 7.

G. HOLST ET AL GASEOUS ELECTRIC DISCHARGE DEVICE Filed Sept. 18. 1934 g? INYENfiZRZ/PM m BY I 77- 1 HIX'IIZORNEY Patented July 20, 1937 UNITED STATES PATENTIIOFFICE Netherlands,

assignors to General Electric Company, a corporation oi New York Application September 18, 1934, Serial No. 744,484 lin Germany September 29, 1933 6 Claims.

The present invention relates to gaseous electric discharge'devices generally.

Gaseous electric discharge lamp devices-and ultra-violet generators of the type having (limcultly vaporizable metals, that is, metals which have a vapor pressure 01 less than 1 mm. at a temperature of 200 0., such as sodium, cadmium, thallium, magnesium and zinc, must be heated to v an elevated temperature to obtain an eifective 10 vapor pressure during the operation of the device.

The discharge current can be used to heat the device to the required temperature but in this case an-appreciable amount of the electrical, energy consumed by the device is transformed into heat 'the pressure in the vessel.

vapor lamps. The boiling point of such materials and thus the'vapor pressure in the container of the lamp device can be controlled by controlling figures.

Referring to Fig. 1 the new and novel lamp rather than light. The efficiency of the device unit comprises a gaseous electric discharge lamp it can be increased by providing means to heat the device to its elevated operating'temperature so that theproportion of the energy consumed by, the device which is transiormed into light rather/ thar:3 heat is increased and the device is more emcien The object of the present invention is to provide simple and effective means for heating the container of a gaseous electric discharge device.

7 Another object of the invention is to provide a lamp unit comprising a gaseous electric discharge metal vapor lamp device which operates at its maximum emciency at an elevated temperature and a heating means for said lamp device. Still further objects and advantages attaching to the device and to its use and operation will be apparcut to those skilled in the art from the following particular description. 7

r In accordance with this object the invention comprises a vessel within which the gaseous electric discharge vapor lamp 'device ismounted, a heat transferring medium in said vessel and a heater for saidemedium. We prefer to use a material which can be boiled as the heat trans- 40 ferring medium. The gaseous electric discharge device is surrounded by hot vapor when the material is boiled and the vapor condenses and flows back to the pool of heated material. Heat v is thus transferred from the heating element to the container of the gaseous electric discharge device and the temperature distribution over the walls of the container is very uniform. when desired a light transmitting, heated liquid flowing over the container is used as the heat transfer-.- ring medium. The heating element is an electric resistance or a gas flame, when desired. Naphthalene is a suitable heat transferring medium for use in connection with sodium vapor lamps and acct-amid and uinoline are suitable for use it in connection with cadmium vapor and cans.

'device having a U-shaped container i which has a thermionic electrode" 2 sealed therein at each end thereof. Said electrodes 2 comprise-a heater element, such as a metal filament, in operative relation to a body of election emitting material,

I such as barium oxide, and are electron emitting when heated. Said electrodes 2 are heated by a special heating current or by the discharge, when desired. The gaseous atmosphere in said container l comprises a rare, starting gas, such as neon, and the vapor of a dimcultly vaporizahle material, such as sodium vapor.

The container 41 is mounted-in an envelope I 3 having a vent therein and is supported in said envelope 3 by the current leads of said electrodes t 2, which leads are sealed into the pinch part a of the stem of said envelope 3. The part of. the current leads 2 in said envelope 3 are covered with insulating material, such as a material comprising alumina, silica-and magnesium xide, to prevent'short circuiting therebetween during the operation of the device. A quantity 5 of naphthalene is placed in the lower part of said envelope 3 and a heater element consisting of an electric resistance, such as a metal filament, covered with heat insulating material, such as asbestos, is mounted exterior to the end of said envelope 3. The envelope 3 is. mounted in a heat conservator such as a double walled jacket hav ing the space between the walls thereof evacuated to reduce the heat losses therefrom, when desired.

During the operation of the above described lamp unit the naphthalene 5 is heated to the vaporizing temperature thereof by the heater ah element t and the envelope 3 is filled with hot naphthalene vapor. The vapor condenses on the walls of said envelope 3 and the condensed naphthalene returns to the lower end of the en- Velo 8. en ded, one ormore light trans- I mitting bafiies are mounted in said envelope 3 to guide the rising, hot naphthalene vapor onto the walls of container I. The temperature of the container l is approximately that of the boiling naphthalene in this case.

The magnitude of the current flow through the lamp device is adjusted to that value at which maximum economy or efiiciency is attained. The vapor pressure in the container I of the lamp device can be controlled by selecting a substance having a boiling temperature which corresponds to the particular vapor pressure desired in the container of the lamp device. The magnitude of the current flow through the lamp and the vapor pressure therein are thus independent of each other and can be separately adjusted to obtain maximum efliciency. Another advantage of the above described apparatus is that a less expensive source of heat than electrical energy is used to maintain the pressure in the lamp device, when desired, which reduces the cost of operating the lamp unit.

The embodiment of the invention illustrated in Fig. 2 of the drawing is similar in all respects to that illustrated in Fig. 1 except that in this embodiment the envelope 3 is supported by a frame I and the gaseous electric discharge lamp device is supported in said envelope 3 by the member 8.

A gas heater 8 is located under said envelope 3 which heats the naphthalene to its boiling temperature. The envelope 3 is gas tight and by varying the gas pressure in the envelope 3 the boiling temperature of the naphthalene and the vapor pressure in the container l of the lamp device is controlled. Said envelope 3 has a condensing chamber at the top thereof into which chamber the gas is driven when the naphthalene is vaporized.

While we'have shown and described and have pointed out in the annexed claims certain novel features of the invention, it will beunderstood that various omissions, substitutions and changes in the forms and details of the device illustrated and in its use and operation may be made by those skilled in the art without departing from the broad spirit and scope of the invention, for example, while we have described our invention with respect to sodium vapor lamps it will be understood of course that We contemplate the use of cadmium, magnesium, thallium, mercury and zinc vapor lamps in our new and novel lamp unit.

What we claim as new and desire to secure by Letters Patent of the United States is:-

1. A lamp unit comprising in combination a gaseous electric discharge metal vapor lamp device, an envelope for said lamp device, a vaporizable material in said envelope and a heating means external to said envelope and in operative relation'to said vaporizable material whereby said lamp device is maintained at an elevated, evenly distributed temperature during the operation of said lamp unit.

2. A lamp unit comprising in combination a gaseous electric discharge metal vapor lamp device comprising a container, electrodes sealed therein and a gaseous atmosphere therein comprising the vapor of a difiicultly vaporizable material, an envelope for said lamp device, a vaporizable material in said envelope and a heating means external to said envelope and in operative relation to said vaporizable material whereby the container of said lamp device is maintained at an elevated, evenly distributed temperature during the operation of said lamp unit.

3. A lamp unit comprising in combination a gaseous electric discharge metal vapor lamp device comprising a container, electrodes sealed therein and a gaseous atmosphere therein comprising sodium vapor, an envelope for said lamp device, a vaporizable material in said envelope and a heating means external to said envelope and in operative relation to said vaporizable material whereby the container of said lamp device is maintained at an elevated, evenly distributed temperature during the operation of said lamp unit.

4. A lamp unit comprising in combination a gaseous electric discharge metal vapor lamp device, an envelope for said lamp device, a heat transferring medium in said envelope and a heating means external to said envelope and in operative relation to said heat transferring medium whereby said lamp device is maintained at an elevated temperature during the operation of said lamp unit.

5. A lamp unit comprising in combination a gaseous electric discharge metal vapor lamp device, an envelope for said lamp device, a vaporizable material in said envelope and a heating means external to said envelope and in operative relation to said vaporizable material whereby the temperature of said lamp device is evenly distributed and is controlled independently of current flow through said lamp device.

' 6.'A lamp unit comprising in combination an electric discharge metal vapor lamp device, an envelope therefor, a pool of vaporizable material in said envelope and a heating means in operative relation to said pool of vaporizable material, said pool being interposed between said heating means and said lamp device whereby said lamp device is maintained at an elevated, evenly distributed temperature during the operation of said lamp unit.

GILLES Horsr. WILLEM m: GROOT. 

